The four spectral tunable light sources based on prism + DMD, grating + DMD, prism based + nematic liquid crystal and multicolor LED based are summarized. The first three spectral tunable light sources work similarly, mainly by projecting a fixed continuous spectrum of light output from the light source into the dispersive element, and then projecting onto the spectral modulation device through the converging lens to form a series of flat on the spectral modulation device. Straight spectral band, through the computer controlled spectral modulation device to change the output to the latter spectral distribution, and finally through the uniform mixing system to produce a prism + DMD-based spectral tunable light source with higher output energy, due to the prism used by the dispersive element, Therefore, its spectral resolution is non-linear, and the spectral resolution is higher at a shorter wavelength, and the uniform temperature source with adjustable color temperature and adjustable brightness. The spectral resolution is lower at longer wavelengths. The spectrally tunable source based on prism + DMD has a spectral resolution that does not change with wavelength due to the grating used by its dispersive element. However, due to the multi-level diffraction of the grating, its energy utilization is low, only 35% of the prism. about. The spectral modulation device based on the prism + nematic liquid crystal uses a nematic liquid crystal. The size of the nematic liquid crystal is large, and there is almost no diffraction phenomenon in the infrared band, so the spectral resolution in the infrared band is high. . The spectrally tunable light source based on multi-color LED has the lowest cost. It is combined by a plurality of monochromatic LEDs with different center wavelengths and different bandwidths, and the brightness and darkness of each LED is controlled by a special control algorithm to emit a whole band. The spectrally adjustable light output, and finally, after the light is mixed by the uniform light mixing system, a uniform light source with adjustable color temperature and adjustable brightness can be formed at the exit.